During the process of producing and harvesting hay it is common to condition stalky plant material such as alfalfa, clover, or the like, by crushing or crimping the stems. This cracks the stems and thereby reduces the time cut plant material remains in the field by increasing the rate at which moisture escapes. U.S. Pat. No. 4,445,313, issued May 1, 1984 in the name of Thomas Elliott et al, discloses a machine illustrative of the general principle of conditioning by crimping. Another example of prior art showing conditioning by crimping is U.S. Pat. No. 4,862,681, issued Sep. 5, 1989 in the name of Gilbert W. Linde et al, which discloses conditioning rolls that crimp and also reciprocate relative to each other to enhance the conditioning.
In addition to crushing or crimping, it is also well known that plant drying can be further enhanced by subjecting the crushed plants to additional conditioning that causes the plant stems to be severely crushed and/or fiberized. This very severe conditioning is commonly referred to as maceration. The various levels of conditioning to which plant materials are subjected has a direct affect on the drying rate. Another benefit of severe conditioning, i.e., maceration, is that it enhances the digestibility of dry hay and hay silage. Maceration is also carried out as a precursor to juice expression from herbage, where industrially valuable products, such as enzymes or nutritional substances are then extracted from the plant juice.
An example of prior art apparatus for macerating plant material, such as forage crops, is shown in U.S. Pat. No. 4,265,076, issued May 5, 1981 in the name of Gary W. Krutz, wherein a self propelled implement is disclosed. The crop material is macerated by a pair of opposing crushing rolls having differential peripheral speeds, after which it is conveyed to a press to form a mat that is discharged rearwardly onto the field over which the implement is being operated.
Another example of prior art apparatus for macerating plant material, also referred to as herbage, is shown in U.S. Pat. No. 5,152,127, issued on Oct. 2, 1992 in the name of Richard G. Koegel et al ("'127 patent"). This patent, hereby incorporated by reference in its entirety, provides an extensive explanation of background material relating to severe conditioning. The '127 patent discloses an implement for processing herbage, such as forage crop material, by cutting standing crop, feeding the cut crop material to a pair of crushing rollers to initially crack the stems of the plants, and subsequently impacting the crushed forage crop material to provide additional fiberization.
In pending application Ser. No. 08/884,277, filed Jun. 27, 1997 in the name of Richard G. Koegel, et al, macerating apparatus is shown that is similar to the apparatus in the '127 patent. The apparatus comprises crushing rolls, an impact rotor and a deflection hood assembly for redirecting impacted crop material back to the impacting rotor for reimpaction.
It should be noted that, although not shown in the drawings of the '127 patent, reference is made to prior art presses for forming mats from macerated material. Insofar as pressing is concerned, a self propelled implement for macerating plant material, such as forage crops, is shown in U.S. Pat. No. 4,265,076, issued May 5, 1981 in the name of Gary W. Krutz, wherein apparatus is disclosed for pressing the macerated plant material. In this implement the crop material is macerated by a pair of opposing crushing rolls with differential peripheral speeds, after which it is conveyed to a press to further enhance drying. The press comprises a roller and a conveyor belt that forms a mat of macerated material that is discharged rearwardly onto the field over which the implement is being operated.
In U.S. Pat. No. 4,332,125, issued Jun. 1, 1982 in the name of Richard D. Holden, harvesting apparatus is disclosed for macerating plant material and subsequently compressing the macerated material to form a mat that is deposited onto the stubble of the freshly cut stems. In this apparatus the mat is formed by exerting pressure in the nip formed between a belt and a series of cooperating rollers arranged with decreasing diameters.
EPC Pat. Application No. EP 0,415,380, filed Aug. 29, 1990 in the name of S. Schuster shows a press for macerated material in which the crop is compressed to a mat between opposing belts that follow a generally S-shaped path. In another EPC Pat. Application, No. EP 0,053,666, filed Oct. 1, 1992 in the name of Klockener-Humbolt-Deutz, a press is shown for macerated material being conveyed along a path between a central roller and a series of planetary rollers with smaller diameters.
In summary, it is acknowledged that the crushing-impact forage conditioner of the type shown in the '127 patent is in the forefront of technology for treating plant material to improve drying rates and digestibility. The high speed impact rotor directly behind the crushing rolls conditions crop by first crushing the tubular structure of plant material by first crushing the stems with the crushing rolls and then fiberizing the crushed stems via the impact rotor. The stems are fiberized along the longitudinal splits that are created during crushing. The degree of conditioning can be altered by varying the force applied by the crushing rolls and the speed and position of the impact rotor. Crop severely conditioned in this manner cannot by simply laid back on the stubble without incurring significant losses. To prevent such loss the severely conditioned crop is pressed into a cohesive mat and deposited on the stubble for support during drying. Its cohesiveness enhances its ability to span gaps in the stubble permitting it to dry completely, and reduce losses during subsequent harvesting.